Statements of Consolidated Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net income for common stock	$ 38,316	$ 28,462
Net unrealized losses on securities:
Net unrealized losses on securities arising during the period, net of tax benefits, of $149 and $414 for the three months ended March 31, 2012 and 2011, respectively	(226)	(626)
Derivatives qualified as cash flow hedges:
Net unrealized holding losses arising during the period, net of tax benefits of $6 for the three months ended March 31, 2011		(9)
Less: reclassification adjustment to net income, net of tax benefits of $37 and $3 for the three months ended March 31, 2012 and 2011, respectively	59	5
Total derivatives qualified as cash flow hedges	59	(4)
Retirement benefit plans:
Less: amortization of net loss, prior service gain and transition obligation included in net periodic benefit cost, net of tax benefits of $2,473 and $631 for the three months ended March 31, 2012 and 2011, respectively	3,873	1,039
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $2,162 and $1,431 for the three months ended March 31, 2012 and 2011, respectively	(3,395)	(2,247)
Total retirement benefit plans	478	(1,208)
Other comprehensive income (loss), net of taxes	311	(1,838)
Comprehensive income attributable to common shareholders	$ 38,627	$ 26,624